Known from patent description No. EP 1586876 A1 is a whistle and a device notifying about using the whistle which generates and transmits an information when the whistle is blow, and lamp apparatuses equipped with receiving antennas situated in corners of a sports playing area and at ends of its half-way line receive radio signals transmitted from the whistle, demodulate whistle information and perform illumination of a lamp in accordance with the intensity of the sound of the whistle, which can be ascertained visually by hearing-impaired persons. The whistle has a body with a mouthpiece, a rolling element contained in resonant chamber of the body vibrations of which are detected by a sensor, a detection section which detects the motion of the rolling element, a whistle information generation section that generates whistle information when motion of the rolling element is detected by the detection section, and a transmitting section equipped with an antenna which transmits the whistle information. Further, the whistle comprises a selection section which produces at its output a signal of a level in accordance with the magnitude of motion of the rolling element and a transmission output adjustment section that adjusts transmission output of the transmitting section. In turn, each of the whistle signalling lamp apparatuses has a receiving section equipped with an antenna which receives a radio signal and demodulates whistle information, and a lamp illumination section and a control section that performs illumination control of the illumination section when whistle information is demodulated by said receiving section.
Description of invention granted U.S. Pat. No. 6,794,989 B2 also discloses a wireless device useful for a hearing impaired person(s) for enabling said person to receive instructions from another person while participating in a sport-related activity. The device comprises a transmitter unit comprising at least two means for receiving a physical impulse for transmitting instructions as a wireless output signal and comprising at least two depressible buttons or keys, and a portable unit adapted to be carried by the hearing impaired person responsive to said wireless signal thereby providing instructions to said person by generating a signal comprising a vibration and then generating a second signal providing a colour illuminating visual signal, which has the form of a different colour illumination corresponding an individual depressible button or key of the transmitter unit.
Also invention described in U.S. Pat. No. 7,173,533 B1 discloses a system alerting sports participants who cannot detect audible signals, a whistle coupled to a referee and operable to emit a first signal, a transceiver coupled to the referee and operable to detect the first signal and emit a second signal in response to the first signal, a remote control device coupled to a coach and operable to emit a third signal, a receiver coupled to a sports participant and operable to receive the second signal and the third signal, and a light coupled to the receiver comprising two bulbs, of which the first light bulb is operable to illuminate in response to the receipt of the second signal, and the second light bulb operable to illuminate in response to the receipt of the third signal. Moreover, the system comprises a vibrating device coupled to the receiver and operable to vibrate in response to receipt of the second signal or the third signal.